Enabling Technologies VLT Town Hallfirefusionpower.org/SOFE2019_Enabling_Technology_Youchison.pdf · 28th IEEE Symposium on Fusion Engineering Enabling Technologies –VLT Town Hall

28th IEEE Symposium on Fusion Engineering

Enabling Technologies – VLT Town HallNuclear Reactor Compatibility Issues

D. Youchison

June 04, 2019


Outline

• Objectives/Requirements for a nuclear reactor (compact pilot plant)

• Major Critical Issues including Gap Metrics for a Nuclear Reactor

• Magnets• Heating• Fueling• PFCs and IVCs• Blankets and Power Conversion (covered by C. Kessel)• Remote Handling

• Potential Next Step Initiatives• Q&A with audience


Pilot plant means long pulse, compact, high density, DT and blanket operations

from J. Rapp

The goal of such a device would be to provide fusion-relevant neutron wall loading Wn1MW/m2, neutron uence 6MW-yr/m2, component testing area of 5-10m2, and continuous on-time (i.e. steady-state operation)for durations in the range of 106s


EU DEMO JA DEMO K-DEMO CFETR (Phase I)Mission Net electricity

(Qeng > 1)

Tritium self-sufficiency

Net electricity (Qeng > 1)


Net electricity (Qeng > 1)


Materials and component testing in fusion environment

Materials & component testing in fusion environment

Full tritium fuel cycle

Pfus 2000 MW 1,500 MW ≥ 300 MW 50–200 MW

TBR > 1.0 > 1.05 > 1.0 ≥ 1.0

Pulse length 2 hr 2 hr to steady state Steady state 1000 s to steady state

Duty factor ~ 70% 30–50%

Pelec 500 MW 200-300 MW (net) ≥ 150 MW (net) N/A

Tritiumbreeding

To be determined – solid and PbLi breeder under consideration

Solid breeder, PWR technology

Solid breeder, PWR technology

Solid breeder, PWR technology, close tritium cycle at ~ 1/10 DEMO scale

Magneticconfiguration

Tokamak Tokamak Tokamak Tokamak

Maintenance Remote handling Remote handling Remote handling Remote handling

Source: Kamendje, Richard et al, International Energy Agency’s Fusion Power Coordinating Committee, Paris,

France, 2016.

International DEMO Concept Requirements

KDEMO

PILOT PLANT


HTS as an enabling technology for high field fusion magnetsProgress has been made in conductor & cable concepts for high field magnets

• Driven primarily by high energy physics community in US but significant efforts

• Focus particular in the field range of 10 T – 20 T were REBCO and Bi-2212 are advantageous

Two private venture fusion efforts are pursuing this enabling technology for their concepts

• But many other national and international labs / universities are pursuing HTS for fusion & high field magnets

Peter Lee, ASC/NHMFLMumgaard NAS comments 2018


Path to fusion magnets over the next ten years could be interestingIssues to consider

Conductor supply and cost?

Conductor and cable piece lengths

Cable Stability and Quench Protections

Radiation Degradation

Prototype Large Coils

Cryogenic Cooling (SCHe, H2, LN2?)

What the appropriate performance metrics?

2000’s DOE Superconductivity Program

$25/kA-m @ 77 K

FusionDepends on who you ask and

the final applications

Current / Current Density (B,T)50 -100 kA

1000 A/mm2 (CS ITER) 4.2 K, 20 K

10 T to 20 T

Conductor on Round Core cables

D.C. van der Laan, SUST 22, 065013 (2009).

CORC cable principle:

Winding many high-temperature superconducting YBCO

coated conductors from SuperPower in a helical fashion with

the YBCO under compression around a small former.

Benefits:

- Very flexible

- Very high currents and current densities

- Mechanically very strong

- Minimum degradation from cabling (< 10 %)

- Current sharing between tapes possible

David Larbalestier, ICMC-CEC U. of Twente, NL, July 7-10, 2014 Slide 39

HTS cables: accelerator and other large magnets

require high cur rent cables (10-20 kA)

Easy path to 2212 cables

t hrough the standard

Ruther f ord cable

Bi-2212 Ruther f ord cables

(Arno Godeke LBNL) w it h

mull i t e insulat ion sleeve

Danko van der Laan

REBCO coated conductor cable wound in

many layers helically on a round form

Other

variants too:

e.g. Roebel

cable

REBCO cables are harder

(Coated Conductor is a

single f i lament ) but

possible (IRL, KIT, CORC,

tw isted stack (MIT)

This CORC geomet ry (van

der Laan et al) is very

at t ract ive as i t t ransposes

and makes a mult i f i lament

cable (of high Ic sui t able

f or large magnet s)

TSTC-Twisted Stacked-Tape Cable

BSCCO-2212 Rutherford cable

400 A/mm2, 4.2 K, 20 T

80 kA, 4.2 K, 10.9 T

2212 Strand 1000 A/mm2

4.2 K 27 T

6 kA 17 T 4.2 K

60 kA, 4.2 K12 T


Strategic investments could enable growth in fusion and other high field areas

It should be thought about the process (time, funds) it took to get to LTS cables that are currently being used for current fusion magnets.

NIFS-FFHR-d1

Prototype Cable Test Facility Large Coil Demonstrations Multi-coil demo facility

Access to cable testing in general is limited by no. of facilities and time

available

SULTAN – split solenoid

11T – 1% over 300 mm, 100 kA

EDIPO – in repair

12 T – 1% over 1 m

NHMFL

14.5 T, 160 mm bore

NIFS (Japan)

13 T, 700mm bore, 50 kA

Which geometry and when (3-5 years)?

TF PF CS Helical

NAS report suggested that perhaps an updated version of the 80’s

international Large Coil Test (LCT)

Six Coils, 8 T, 11 kA, NbTi


ITER AntennaICRF Issues and Gaps• Plasma heating and current drive using the Ion Cyclotron

Range of Frequencies (ICRF) are important elements for the success of fusion1,2

• Most DEMO concepts identify ICRF as a main heating system

• Launching structures for ICRH or LHCD must operate in a high radiation, high heat-flux environment

• The exposed antenna surfaces must be resistive to high heat (1-10 MW/m2) and neutron fluxes with acceptable levels of impurity production

• Many reactor concepts will require operating at ~700 °C

• The issues and gaps with creating reliable ICRF operation cut across the disciplines of plasma theory and simulation, RF technology, materials, diagnostics, and reactor engineering (reliability and maintenance)

ITER Faraday Shield

FNFS

1Greenwald Panel FESAC Report

(http://science.energy.gov/~/media/fes/fesac/pdf/2007/Fesac_planning_report.pdf)2Research Needs for Magnetic Fusion Energy Sciences Final Report

(https://www.burningplasma.org/web/ReNeW/ReNeW.report.press1.pdf)

http://science.energy.gov/~/media/fes/fesac/pdf/2007/Fesac_planning_report.pdf


Antennas operate in a harsh environment• Physics issues: antenna near-field interactions with the plasma in the scrape

off layer (SOL) are not well understood:• The formation of the RF plasma sheath: enhanced particle and energy fluxes on

the antenna and on surfaces intersected by the magnetic field lines connected to/near the antenna

• The parasitic RF losses in SOL region• RF breakdown/arcing, which is one of the main power-limiting issues operating in

the plasma environment

• Material issues: antenna-compatible materials operating in a CW high heat/neutron flux environment are not validated:

• Thermal and neutron-induced stresses at joints/grain boundaries (antenna structural stability)

• Cracking due to void formation (possible arc initiation)• Erosion of coatings and dust production (possible arc initiation)

• Reliability issues: Long pulse operation of the antenna and source

• Solving these problems will likely require an approach that combines modeling/design with validation of the models on dedicated RF Coupling Experiments/Test Stands and Confinement Devices

Hot spots on Tore Supra antenna

RF breakdown/arcing

Surface changes from PMI

S Lindig et al., T145 (2011)

014039

Y Ueda et al., Fus. Sci.

Technol. 52 (2007) 513


ECH challenges

• Steady state, 1 MW+ gyrotrons, high frequencies and lifetimes

• Cooled, high power miter bends, switches and polarizers

• Window development

• Neutron damage to mirrors

• HFS launch, integration of antennas

and WGs into blankets necessary for

a nuclear facility.

Problem: too many ports!


Fuel Throughput in Fusion Plasmas

Needs Dramatic Extension from Previous Experiments

• DT fuel throughput for ITER and beyond is well beyond what has been achieved in previous devices. Recirculation of DT within the

pellet system makes the design much more complicated.

ITER-1

ITER-DT

DEMO

LHD

ATF

TRIAM-1M

Plasma Duration (s)

Fu

el T

hro

ug

hp

ut

(Pa-m

3)

1 Day1 Hr1 Min

Tore Supra

DIII-D

TFTR

JT60JET

DT

*Requires recirculation

ST

NFPP

Pure Tritium Extrusion Pure Tritium Pellet

Hydrogen, Deuterium and Tritium Pellets

W7-X


Fusion Exhaust Pumping Schemes

•Batch Cryopumps – ITER Method T2 inventory, Deflagration limit, Thermal cycling, Valve cycling, He pumping

•Continuous Cryopump – Snail pump prototype developed and tested by Foster at ORNL

- Mechanical scraper- Cryo separation- Helium compression for conventional pumping- Pellet formation from exhaust concept tested

•Liquid Metal Pumps (KIT): – Diffusion pump and liquid metal ring roughing pump

- Needs separation of impurities and helium to provide direct recirculation to fueling system

- Super permeable membrane separation?

ITER

Efficient tritium compatible pumping is needed

to remove the exhaust gases from the plasma

(transport losses and burn byproducts).


Transient Mitigation using Pellet Technology

• Disruption Mitigation

• Shattered pellet injector (SPI) experiments on DIII-D deliver deep penetration and assimilation to maximize dispersal of plasma energy into radiation to spread out the heat over greatest area possible

• Large High-Z (Ar, Ne) pellets developed for thermal mitigation and runaway electron dissipation

• SPI experiments on JET and KSTAR are planned in support of ITER DMS

• ELM Pacing

• Experiments on DIII-D demonstrated peak heat flux deposited in the divertor per ELM decreases with increasing injection frequency

SPI-II with Gas Manifold

Three cryogenically cooled barrels inside the guard vacuum


Plasma Facing ComponentsNew challenges in a nuclear facility:• Higher q” and temperatures from compact plasmas• Long pulse or steady state operation• Active cooling required (high pressure, high temperature, chemistry). Water is

not coolant of choice.• Corrosion, transport and fouling (crud activation)• Modularity compatible with blanket and divertor concepts – (affects manifolds, RH,

shielding, ports, part count, connections, bake-out)

• Integral FW/blanket and advanced divertors• Manifolding and welding• Remote handling and repair• EM loads particularly during disruptions• Joining and additive mfg.• Engineering Diagnostics, Performance monitoring & RAMI• Neutron irradiation -> activation• Tritium absorption and permeation• Disruption/ELM melting• Erosion and dust formation

*A nuclear reactor cannot be a versatile plasma research platform


PFC development path from PMI Workshop Report

actively cooled

W & RAFM X

X

• multi-channel• manifolding• mounts• diagnostics

• armor• heatsink• coolant

X

U.S. can no longer fabricate or test advanced helium-cooled PFCs

All-tungsten porous media heat sink (left), all-copper

porous media heat sink (middle), all-moly porous

foam tee-tube heat sink (right)

Multi-channel helium-cooled TZM/Moly heat

sink with moly foam: 3D CAD (left panel) and

fabricated test device (right panel)

TRL3

TRL4

TRL2 TRL2

TRL4

1990 2020

0.50”0.62”0.75” (for Swagelok)W Foam

CVD W Tube (0.060” wall)CVD Nb Sleeve (0.065” wall)

1.25”0.75”

8.5”6.0”2.0”

TRL2


New Initiative in Advanced Helium Cooling

• Helium cooling for FW/Blanket and divertor• PFCs and power conversion HXs

• RAFM and W materials – additive manufacturing• Manifold development• Closed helium flow loop, 10 MPa, 1 kg/s• E-beam HHF facility with microwave and induction heating

In-vessel Components LM PFCs


Remote Handling Technology

• Reactor systems must incorporate RH designs from the very beginning

• Large Hot Cell repair bays and shielded transport systems are required

• Large component assembly/disassembly with precision

• Sealing of large faces to maintain vacuum – how many making and breaking

can a surface take? Are there better methods for sealing components to ensure

vacuum?

• For large component replacement with very high radiation (Tritium and other

airborne contamination), how to design an effective hot cell? Is an overhead

bridge crane system still the best option?

• What is the best design for an airlock that enables robotic transfers?

Remote

Controlled

Servomanipulator

Target Remote Handling

Control Room

Advanced Human–Machine Interfaces

Remote Handling Sensor/Actuators

• How to disconnect and reconnect myriads of fluid and vacuum lines? Are there better ways than cutting and welding?

• Develop radiation tolerant cameras that can withstand radiation levels of >107 Gy. Vacuum tube (Vidicon & Chalnicon) cameras can withstand 106 Gy, but have poor resolution. Rad resistant fiber optics.

• Do LiDAR and ultrasonic offer possibilities for some areas of diagnostics? Need improved synthetic vision and VR simulation.

• Do electronics need to go to vacuum tubes or can CMOS with shielding still be a viable option? What about GaAs rad hard chips?

• Large component placement – hydraulic, air, or electric actuation. Non organic based hydraulic system?

ITER casks Cassette manipulators


Q&A

Some New Initiatives:

• Advanced helium cooling for PFCs & HHF test facility- could be part of a larger blanket test facility

• RH as part of FESS system studies• HTSC joint development – SC magnet test stand• HFS launch RF heating initiative• Steady-state pellet fueling

Documents

Enabling Technologies VLT Town Hallfirefusionpower.org/SOFE2019_Enabling_Technology_Youchison.pdf · 28th IEEE Symposium on Fusion Engineering Enabling Technologies –VLT Town Hall